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INTRODUCTION: Alzheimer disease (AD) is the most common cause of dementia and is considered one of the main causes of disability and dependence affecting quality of life in elderly people and their families. Current pharmacological treatment includes acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine) and memantine; however, only one-third of patients respond to treatment. Genetic factors have been shown to play a role in this inter-individual variability in drug response. DEVELOPMENT: We review pharmacogenetic reports of AD-modifying drugs, the pharmacogenetic biomarkers included, and the phenotypes evaluated. We also discuss relevant methodological considerations for the design of pharmacogenetic studies into AD. A total of 33 pharmacogenetic reports were found; the majority of these focused on the variability in response to and metabolism of donepezil. Most of the patients included were from Caucasian populations, although some studies also include Korean, Indian, and Brazilian patients. CYP2D6 and APOE are the most frequently studied biomarkers. The associations proposed are controversial. CONCLUSIONS: Potential pharmacogenetic biomarkers for AD have been identified; however, it is still necessary to conduct further research into other populations and to identify new biomarkers. This information could assist in predicting patient response to these drugs and contribute to better treatment decision-making in a context as complex as ageing.

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INTRODUCTION: Parkinson's disease (PD) is a common neurodegenerative disease which begins in adulthood. Its incidence in Mexico is estimated to be 40-50 cases per 100,000 inhabitants/year and is the fourth reason for medical care in the National Institute of Neurology and Neurosurgery. The protein alpha-synuclein, SNCA, plays a key role in the pathology of PD, and its polymorphisms have been associated with an increased risk of developing the disease. AIM: To evaluate the risk of PD represented by the polymorphisms rs2619364, rs2619363, rs2736990, rs7684318, rs17016074, rs356219, rs356220 and rs356203 of SNCA in a sample of Mexican subjects. SUBJECTS AND METHODS: Altogether 171 patients diagnosed with PD and 171 gender- and age-paired controls were assessed by means of real-time polymerase chain reaction, and a statistical analysis was performed to determine the association between the polymorphisms and the disease. RESULTS: The SNCA variants rs356220, rs356203, rs7684318 and rs2736990 were associated with the disease and form two haplotypes with a high risk of developing sporadic PD in the Mexican population. CONCLUSIONS: Variations in SNCA are a risk factor for the development of PD and can act as specific genetic biomarkers as a diagnostic support tool in sporadic PD for Mexican mestizo patients.

TITLE: Frecuencia de polimorfismos de nucleotido unico y haplotipos de alfa-sinucleina asociados con la enfermedad de Parkinson esporadica en poblacion mexicana.Introduccion. La enfermedad de Parkinson (EP) es una entidad neurodegenerativa comun de inicio en la etapa adulta. Su incidencia en Mexico se estima en 40-50 casos por 100.000 habitantes/año y constituye la cuarta causa de atencion medica en el Instituto Nacional de Neurologia y Neurocirugia. La proteina alfa-sinucleina, SNCA, es clave en la patologia de la EP y sus polimorfismos se han asociado a un riesgo aumentado de desarrollarla. Objetivo. Evaluar el riesgo que representan los polimorfismos rs2619364, rs2619363, rs2736990, rs7684318, rs17016074, rs356219, rs356220 y rs356203 de SNCA en una muestra de sujetos mexicanos para la EP. Sujetos y metodos. Se evaluaron 171 pacientes con diagnostico de EP y 171 controles pareados por sexo y edad mediante reaccion en cadena de la polimerasa en tiempo real, y se realizo un analisis estadistico para determinar la asociacion de los polimorfismos con la enfermedad. Resultados. Las variantes rs356220, rs356203, rs7684318 y rs2736990 de SNCA estan asociadas a la enfermedad y forman dos haplotipos de riesgo elevado para desarrollar EP esporadica en la poblacion mexicana. Conclusiones. Las variaciones en SNCA son un factor de riesgo para desarrollar EP y pueden ser biomarcadores geneticos especificos para pacientes mestizos mexicanos como herramienta de apoyo diagnostico en la EP esporadica.

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Alzheimer's disease is a degenerative disorder of the central nervous system which causes progressive memory and cognitive decline during mid to late adult life and is accompanied by a wide range of neuropathologic features including extracellular amyloid plaques and intra-neuronal neurofibrillary tangles. Four genetic loci for Alzheimer's disease have been identified. They are the amyloid precursor protein gene on chromosome 21, a gene for early onset autosomal dominant form on chromosome 14, another gene on chromosome 1, and the risk-modifying gene apolipoprotein E on Chromosome 19. The etiology is heterogeneous and complex, and additional Alzheimer's disease genes remain to be found. The genes identified in the inherited forms are now being used to understand the pathogenesis of the disease.

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Three highly informative markers genetically linked to Huntington's Disease (HD) were used for diagnosis of HD in Mexican patients, two polymorphic HindIII sites located at D4S10 locus and one VNTR marker at D4S111 locus (VNTR-111). Forty chromosomes from healthy subjects were tested in order to evaluate the informativeness of the probes. The RFLP HindIII 1 and 2 and the VNTR-111 probes showed a heterozygosity of 0%, 45%, and 60%, respectively. Five families were analyzed, of these, only in two the markers used were informative. In one of them, six members showed a decreased risk of inheritance of the mutant gene for Huntington's Disease with 95% accuracy (1).

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